Conventionally, to improve high speed durability and road noise, pneumatic tires are disclosed in, for example, Unexamined Japanese Patent Application Publication Nos. 11-34610 and 2001-180225, having a belt cover ply disposed radially outwardly of the belt plies, the belt cover ply extending beyond the edges of the belt plies. The belt cover ply has such extension portions, thereby increasing a hoop effect in the shoulder portions, resulting in that high speed durability is improved and road noise is reduced.
However, when the extension portions extend 10 mm or greater in the axial direction of the tire to further increase the above effect by the belt cover ply, an increase in the amount of heat generated in the shoulder portions, due to repeated deformation received during rolling of the tire, increases a loss in energy, thereby encountering a problem of deteriorating rolling resistance.
Also, the extension portions of 10 mm or greater depend radially inward from the edges of the belt plies when a green tire is formed. As a result, the difference between the circumferential lengths of the center side and extension portions of the belt cover ply is larger, so that wrinkles are created in the extension portions when the green tire is molded during curing; the wrinkling becomes one of the causes that degrade uniformity of a cured tire.